John has a bag of different colored marbles. He has 6 red marbles, 3 blue marbles, 7 yellow marbles, and 5 green marbles. If John reaches into the bag and randomly pulls out a marble, what is the probability that the marble will be blue? (If necessary, round to the nearest tenth.)
A.
14.3%
B.
28.6%
C.
30.0%
D.
85.7%